Estimating wellbore cement properties

A method of estimating properties of wellbore cement by penetrating the cement, and monitoring the amount of energy or power required for penetrating the cement. Penetrators include a drill bit that bores into the cement, and probes or pins that are forced into the cement. The energy or power monitored can be current and/or voltage supplied to a motor that drives the drill bit or probe. Comparing the monitored energy or power with that required to penetrate a reference cement sample of known properties can yield information about the cement being sampled. When the wellbore is lined with multiple coaxially disposed strings of casing with cement between adjacent strings and on the outer surface of the outer string; the method further includes obtaining core samples from portions of each string, each layer of cement, and formation adjacent the wellbore.